GaN HEMTs are attractive devices for high-power and high-frequency applications due to their superior electron mobility and wide bandgap characteristics. However, they are also susceptible to other phenomena, such as current collapse and kink effects, which can reduce their performance and dependability. Precise material models are crucial to accurately represent the fundamental physics of GaN HEMTs. These model stake into account impact ionization, trap capture and emission kinetics, and other related physical procedures. Additionally, it is necessary to properly incorporate surface and interface effects into the models because they are crucial to both kink effects and current collapse. Understanding the behavior of the device and developing optimized circuits depend on modeling the kink effect in GaN HEMTs. Various methods have been devised to capture and reproduce the kink effect, including empirical modeling and physical models. To study the kink effect detected in S22 for AlGaN/GaN HEMTs using a physics-based model AlGaN/GaN HEMT must first undergo thorough RF characterization at a range of bias settings and RF power levels. The S-parameters (S11 and S22) must be measured to examine the device’s transmission and reflection characteristics. At higher drain bias levels or RF power levels, the kink effect is often seen as an abrupt decrease in the S22 parameter (reflection coefficient).Then, a physics-based model is created to comprehend the underlying physical principles driving the kink effect. The kink phenomena in AlGaN/GaN high-electron-mobility transistors require the development of a large-signal model that encompasses all aspects of device behavior, including the kink phenomenon under high-power and high-voltage situations.